A weighty matter

Measuring your weight using the body mass index is outdated and flawed, say experts. KATE BOHDANOWICZ reports on a new system which is claimed to be more accurate

DANGER Obesity poses a serious threat to your health DANGER: Obesity poses a serious threat to your health

For more than 100 years a healthy weight has been defined by the body mass index (BMI). Using height and weight measurements alone, a person is categorised as underweight, normal, overweight or obese.

But this one-size fits all technique, which does not take into consideration fat and muscle distribution, is far from perfect. Brad Pitt and Russell Crowe might be Hollywood pin-ups but, according to the BMI scale, they are overweight. And the muscular frame boasted by rugby star Jonny Wilkinson tips him into the obese class used by BMI.

The body volume index (BVI) scanner is a new technique which measures weight in a more detailed way. It takes into account body shape, muscle mass and the location of fat stored in the body.

Although still a work in progress, BVI was recently presented at a European Obesity Conference and a two-year clinical research study will start next month. It is hoped that by 2009 walk-in scanners will be available in the health industry. “It would be useful in pre-op assessments prior to anaesthetic,” says Richard Barnes, managing director of Birmingham-based company Select Research. He devised the scanner for clothes firms to mass produce items in various sizes before realising it could be used for medical purposes.

“For example, it can tell you the thickness of your neck, which may determine whether you can use breathing apparatus under anaesthetic,” he says.

A few weeks ago Anjelica Allan was refused a hip replacement as she was deemed too heavy for surgery. According to the BMI scale Anjelica, 49, at 5ft 7in and 13stone, was obese and 6lb too heavy to be operated on. But Anjelica is a dress size 14, which is smaller than the UK average of size 16.

“If you have a BMI of 30, you are clinically obese but you might be healthy,” says Richard. “I would like to see the scanner available in weight management clinics as a form of obesity control, in hospitals and possibly in private fitness clinics.”

The BVI scanner takes around seven seconds to create a virtual model of a person’s shape, which is then uploaded on to a computer for analysis. The BVI system will be able to “read” body shape and distinguish between muscle and fat by each body section. The body is broken down into isolated parts to see exactly where fat is distributed. It also provides waist, abdomen and hip measurements.

Your Health asked four people to try out the new system and measured them on the BMI scale, as well as the BVI scale.

Ashley Grainger

19, a student from Worcester Park, Surrey

Height: 6ft 1in

Weight: 13st 7lb

BMI: 25.5, classed as overweight

“This is proof that BMI does not work in all circumstances, especially with men with muscular bodies,” says Dr Marjon Monfared, leading obesity expert and author of The Slim Clinic.

“The scan shows Ashley to be perfectly proportioned and very healthy. His chest is carrying the greatest single proportion of his weight (38 per cent), which is how the perfect male body should be. ‘Overweight’ and ‘obese’ are very negative labels, especially for young men, and can lead to crash dieting and unnecessary weight loss.”

Unlike BMI, the BVI system will be able to “read” body shape and distinguish between muscle and fat by body section.

BVI: 21-22, which shows Ashley is normal and healthy.

Nessie Maclay

34, a greetings card designer from London

Height: 5ft 5in

Weight: 9st 10lb

BMI: 22, classed as normal

Nessie gave birth to her third child seven months ago and is trying to get down to her pre-baby weight of nine stone. Although she is 10lb off her target weight and has a normal BMI, her waist to hip ratio – which dictates whether you are pear or apple shaped – is 1, when it should be lower.

“Although Nessie looks healthy, her waist to hip ratio should be 0.9 or below,” says Dr Monfared. Having a waist to hip ratio of 1 or above means you are carrying too much weight on the stomach or upper torso. This can lead to raised cholesterol and blood pressure, which can lead to heart disease or stroke.

“This is an example of BMI being falsely reassuring,” adds Dr Monfared. Although Nessie looks slim and rates perfectly well on the BMI scale, BVI highlights the additional weight she is carrying round her middle and the associated risk.

BVI: 23-24, slightly higher than BMI due to the excess weight that Nessie is carrying round the abdominal area.

Rachel roberts

29, a PR consultant from Witherley, Leicestershire, is 28 weeks pregnant

Height: 5ft 4in

Weight: 14stone

BMI: 33.6, classed as obese

Rachel was overweight before she was pregnant and the BVI scanner shows she is carrying extra weight on her arms, thighs and pelvis. She says her BMI was 30 when she was three months pregnant, which means she has since put on considerable weight and not just on her stomach.

“It is important to monitor women throughout pregnancy,” says Dr Monfared. “Bigger women have bigger babies, which can lead to gestational diabetes and raised blood pressure.”

When calculating weight distribution on pregnant women, BVI takes into account water retention, excess weight outside the abdominal and pelvic areas and the weight of the baby at that stage of  pregnancy.

BVI: 29-30, overweight. However, Rachel is placed in a lower category than BMI as her water retention is taken into account, as well as the baby’s weight.

Brian Catt

64, a marketing director from Sunbury-on-Thames, Middlesex

Height: 5ft 9din

Weight: 14st 7lb

BMI: 29.4, classed as virtually obese

“Looking at Brian’s body scan, it is apparent that he is carrying too much weight on his stomach,” says Dr Monfared.

“His waist measures 42.9in, which is high. Ideally, men should aim for a waist circumference of less than 40in. By carrying too much weight round his middle, he is at a greater risk of developing heart disease, gall stones and Type 2 diabetes.”

While BMI gives no indication of where weight is carried on the body, BVI takes the volume of the abdomen into account when designating a risk figure.

Extra weight round the stomach area is an indication of greater health risk.

BVI: 29-30, the same as BMI. The volume around his abdomen makes him a risk factor.

● For further information on BVI, visit www.bodybenchmark.org

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